Bump xunit from 2.7.0 to 2.9.1 in /src

Bumps [xunit](https://github.com/xunit/xunit) from 2.7.0 to 2.9.1.
- [Commits](xunit/xunit@2.7.0...2.9.1)

---
updated-dependencies:
- dependency-name: xunit
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Directory.Build.props

@@ -58,6 +58,6 @@
         <SwashbuckleAspNetCoreSwaggerUIVersion>5.5.1</SwashbuckleAspNetCoreSwaggerUIVersion>
         <SwashbuckleAspNetCoreSwaggerVersion>5.5.1</SwashbuckleAspNetCoreSwaggerVersion>
         <XunitRunnerVisualstudioVersion>2.4.2</XunitRunnerVisualstudioVersion>
-        <XunitVersion>2.7.0</XunitVersion>
+        <XunitVersion>2.9.1</XunitVersion>
     </PropertyGroup>
 </Project>